Structural insights into the role of GTPBP10 in the RNA maturation of the mitoribosome.

Mitochondria contain their own genetic information and a dedicated translation system to express it. The mitochondrial ribosome is assembled from mitochondrial-encoded RNA and nuclear-encoded ribosomal proteins. Assembly is coordinated in the mitochondrial matrix by biogenesis factors that transiently associate with the maturing particle. Here, we present a structural snapshot of a large mitoribosomal subunit assembly intermediate containing 7 biogenesis factors including the GTPases GTPBP7 and GTPBP10. Our structure illustrates how GTPBP10 aids the folding of the ribosomal RNA during the biogenesis process, how this process is related to bacterial ribosome biogenesis, and why mitochondria require two biogenesis factors in contrast to only one in bacteria.

First Experience With Postoperative Transcranial Ultrasound Through Sonolucent Burr Hole Covers in Adult Hydrocephalus Patients.

BACKGROUND: Managing patients with hydrocephalus and cerebrospinal fluid (CSF) disorders requires repeated head imaging. In adults, it is typically computed tomography (CT) or less commonly magnetic resonance imaging (MRI). However, CT poses cumulative radiation risks and MRI is costly. Ultrasound is a radiation-free, relatively inexpensive, and optionally point-of-care alternative, but is prohibited by very limited windows through an intact skull. OBJECTIVE: To describe our initial experience with transcutaneous transcranial ultrasound through sonolucent burr hole covers in postoperative hydrocephalus and CSF disorder patients. METHODS: Using cohort study design, infection and revision rates were compared between patients who underwent sonolucent burr hole cover placement during new ventriculoperitoneal shunt placement and endoscopic third ventriculostomy over the 1-year study time period and controls from the period 1 year before. Postoperatively, trans-burr hole ultrasound was performed in the clinic, at bedside inpatient, and in the radiology suite to assess ventricular anatomy. RESULTS: Thirty-seven patients with sonolucent burr hole cover were compared with 57 historical control patients. There was no statistically significant difference in infection rates between the sonolucent burr hole cover group (1/37, 2.7%) and the control group (0/57, P = .394). Revision rates were 13.5% vs 15.8% (P = 1.000), but no revisions were related to the burr hole or cranial hardware. CONCLUSION: Trans-burr hole ultrasound is feasible for gross evaluation of ventricular caliber postoperatively in patients with sonolucent burr hole covers. There was no increase in infection rate or revision rate. This imaging technique may serve as an alternative to CT and MRI in the management of select patients with hydrocephalus and CSF disorders.

Conserved and specialized functions of Type VII secretion systems in non-tuberculous mycobacteria.

Non-tuberculous mycobacteria (NTM) are a large group of micro-organisms comprising more than 200 individual species. Most NTM are saprophytic organisms and are found mainly in terrestrial and aquatic environments. In recent years, NTM have been increasingly associated with infections in both immunocompetent and immunocompromised individuals, prompting significant efforts to understand the diverse pathogenic and signalling traits of these emerging pathogens. Since the discovery of Type VII secretion systems (T7SS), there have been significant developments regarding the role of these complex systems in mycobacteria. These specialised systems, also known as Early Antigenic Secretion (ESX) systems, are employed to secrete proteins across the inner membrane. They also play an essential role in virulence, nutrient uptake and conjugation. Our understanding of T7SS in mycobacteria has significantly benefited over the last few years, from the resolution of ESX-3 structure in Mycobacterium smegmatis, to ESX-5 structures in Mycobacterium xenopi and Mycobacterium tuberculosis. In addition, ESX-4, considered until recently as a non-functional system in both pathogenic and non-pathogenic mycobacteria, has been proposed to play an important role in the virulence of Mycobacterium abscessus; an increasingly recognized opportunistic NTM causing severe lung diseases. These major findings have led to important new insights into the functional mechanisms of these biological systems, their implication in virulence, nutrient acquisitions and cell wall shaping, and will be discussed in this review.

Structure of the mycobacterial ESX-5 type VII secretion system pore complex.

The ESX-5 type VII secretion system is a membrane-spanning protein complex key to the virulence of mycobacterial pathogens. However, the overall architecture of the fully assembled translocation machinery and the composition of the central secretion pore have remained unknown. Here, we present the high-resolution structure of the 2.1-megadalton ESX-5 core complex. Our structure captured a dynamic, secretion-competent conformation of the pore within a well-defined transmembrane section, sandwiched between two flexible protein layers at the cytosolic entrance and the periplasmic exit. We propose that this flexibility endows the ESX-5 machinery with large conformational plasticity required to accommodate targeted protein secretion. Compared to known secretion systems, a highly dynamic state of the pore may represent a fundamental principle of bacterial secretion machineries.

Low Plasma Appearance of (+)-Catechin and (-)-Catechin Compared with Epicatechin after Consumption of Beverages Prepared from Nonalkalized or Alkalized Cocoa-A Randomized, Double-Blind Trial.

Flavan-3-ols are claimed to be responsible for the cardioprotective effects of cocoa. Alkalized cocoa powder (ALC), commonly used for many non-confectionary products, including beverages, provides less (+)-catechin, (-)-epicatechin, and procyanidins and more (-)-catechin than nonalkalized cocoa powder (NALC). This may affect the plasma appearance of monomeric flavan-3-ol stereoisomers after consumption of NALC vs. ALC. Within a randomized, crossover trial, 12 healthy nonsmokers ingested a milk-based cocoa beverage providing either NALC or ALC. Blood was collected before and within 6 h postconsumption. (+)-Catechin, (-)-catechin, and epicatechin were analyzed in plasma by HPLC as sum of free and glucuronidated metabolites. Pharmacokinetic parameters were obtained by a one-compartment model with nonlinear regression methods. For epicatechin in plasma, total area under the curve within 6 h postconsumption (AUC0-6h) and incremental AUC0-6h were additionally calculated by using the linear trapezoidal method. After consumption of NALC and ALC, (+)-catechin and (-)-catechin were mostly not detectable in plasma, in contrast to epicatechin. For epicatechin, total AUC0-6h was different between both treatments, but not incremental AUC0-6h. Most kinetic parameters were similar for both treatments, but they varied strongly between individuals. Thus, epicatechin is the main monomeric flavan-3-ol in plasma after cocoa consumption. Whether NALC should be preferred against ALC due to its higher (-)-epicatechin content remains unclear with regard to the results on incremental AUC0-6h. Future studies should investigate epicatechin metabolites in plasma for a period up to 24 h in a larger sample size, taking into account genetic polymorphisms in epicatechin metabolism and should consider all metabolites to understand inter-individual differences after cocoa intake.

Quantitative evaluation of the beneficial effects in the mdx mouse of epigallocatechin gallate, an antioxidant polyphenol from green tea.

In two separate previous studies, we reported that subcutaneous (sc) or oral administration of (-)-epigallocatechin-3-gallate (EGCG) limited the development of muscle degeneration of mdx mice, a mild phenotype model for Duchenne muscular dystrophy (DMD). However, it was not possible to conclude which was the more efficient route of EGCG administration because different strains of mdx mice, periods of treatment and methods of assessment were used. In this study, we investigated which administration routes and dosages of EGCG are the most effective for limiting the onset of dystrophic lesions in the same strain of mdx mice and applying the same methods of assessment. Three-week-old mdx mice were injected sc for 5 weeks with either saline or a daily average of 3 or 6 mg/kg EGCG. For comparison, age-matched mdx mice were fed for 5 weeks with either a diet containing 0.1% EGCG or a control diet. The effects of EGCG were assessed quantitatively by determining the activities of serum muscle-derived creatine kinase, isometric contractions of triceps surae muscles, integrated spontaneous locomotor activities, and oxidative stress and fibrosis in selected muscles. Oral administration of 180 mg/kg/day EGCG in the diet was found the most effective for significantly improving several parameters associated with muscular dystrophy. However, the improvements were slightly less than those observed previously for sc injection started immediately after birth. The efficacy of EGCG for limiting the development of dystrophic muscle lesions in mice suggests that EGCG may be of benefit for DMD patients.

Current analysis of endoloops in appendiceal stump closure.

BACKGROUND: An inadequate closure of the appendix stump leads to intra-abdominal surgical site infection. The effectiveness of various appendiceal stump closure methods, for instance, staplers or endoloops, was evaluated. Many analyses show that the use of a stapler for transection and closure of the appendiceal stump lowers the risk of this infection but a statistically significant risk of postoperative intra-abdominal abscess or wound infection was not considered in any randomized study. The aim of this study was to evaluate the complications after using endoloops in a high-volume center. METHODS: The data of 1,790 patients who underwent laparoscopic appendectomy between January 1998 and December 2006 and a single center was prospectively acquired. The standard procedure used was an appendiceal stump closure using endoloops and a selective use of staplers. The outcome criteria for inclusion in the study were intra-abdominal abscess formations, other specific intraoperative and postoperative complications, and the different costs of the operation. RESULTS: Laparoscopic appendectomy was performed in 1,790 (80.8%) patients and open appendectomy in 425 (19.2%) patients. Conversion to open surgery occurred in 74 (4.13%) patients. Laparoscopic appendectomy with stump closure using endoloops was performed in 1,670 (97.3%) patients and stump closure using a stapler in 46 (2.7%) patients. Among 851 patients with acute appendicitis, 284 patients with perforated appendicitis, and 535 patients with other or no pathology, the rate of intra-abdominal abscess after using an endoloop or a stapler was not significantly different (1.5 vs. 0%, p = 0.587; 3.5 vs. 4.2%, p = 0.870; 0.7% vs. 0, p = 0.881, respectively). There were no significant differences between the endoloop group and the stapler group with respect to the other specific intraoperative and postoperative complications. CONCLUSION: This study shows the safety of the endoloop for clinical daily routine. A selective procedure for stump closure has been established. Appendiceal stump closure using an endoloop is an easy, safe, and cost-effective procedure.

Chiral separation of (+)/(-)-catechin from sulfated and glucuronidated metabolites in human plasma after cocoa consumption.

Cocoa is well-known to be rich in flavan-3-ols. Previous analyses have established that alkaline treatment of cocoa beans results in epimerization of (-)-epicatechin to (-)-catechin and (+)-catechin to (+)-epicatechin. Now, the question is whether both epimers can be absorbed by the human organism. This paper describes sample preparation and an HPLC method for chiral determination of (+)/(-)-catechin from sulfated and glucuronidated metabolites in human plasma. The sample preparation includes enzymatic hydrolysis of the catechin metabolites, and solid-phase extraction (SPE). A PM-gamma-cyclodextrin column is used with a coulometric electrode-array detection (CEAD) system. The recovery of catechin ranges from 89.9 to 96.8%. The limit of detection is 5.9 ng mL(-1) for (-)-catechin and 6.8 ng mL(-1) for (+)-catechin, and the limit of quantification is 12.8 ng mL(-1) for (-)-catechin and 16.9 ng mL(-1) for (+)-catechin. The relative standard deviation of the method ranges from 0.9 to 1.5%. This method was successfully applied to human plasma after consumption of a cocoa drink. In one human self-experiment, (+)-catechin and (-)-catechin were found in human plasma, but metabolism of the two enantiomers differed.